Electrostatic drive type mems element, manufacturing method thereof, optical mems element, optical modulation element, glv device, and laser display

ABSTRACT

The present invention provides an electrostatic drive type MEMS device and a manufacturing method thereof, in which flattening the surface of a driving side electrode, improving performance, and further the improvements of the degree of freedom of designing in the manufacturing process are implemented. In addition, the present invention provides a GLV device using this MEMS device, and further a laser display using this GLV device.  
     In the present invention an electrostatic drive type MEMS device includes a substrate side electrode and a beam having a driving side electrode driven by electrostatic attraction force or electrostatic repulsion force that acts between the substrate side electrode and driving side electrode, in which the substrate side electrode is formed of an impurities-doped conductive semiconductor region in a semiconductor substrate.

TECHNICAL FIELD

[0001] The present invention relates to an electrostatic drive type MEMSdevice and a manufacturing method thereof, an optical MEMS device, alight modulation device, a GLV device and a laser display.

BACKGROUND ART

[0002] With the advances in microscopic manufacturing technology, muchattention has been focused on so-called micro-machine (MEMS: MicroElectro Mechanical Systems, ultra-miniature electric, mechanicalcompound) devices and miniature devices in which MEMS devices areincorporated.

[0003] A MEMS device is a device that is formed on a substrate such as asilicon substrate, glass substrate or the like as a microscopicstructure, and electrically and further, mechanically unites a drivingbody outputting mechanical driving force with a semiconductor integratedcircuit or the like that controls the mechanical body. A basic featureof the MEMS device is that a mechanically structured driving body isincorporated in a part of the device, and the driving body iselectrically driven by the use of coulombic attraction force betweenelectrodes or the like.

[0004]FIGS. 13 and 14 show a typical composition of an optical MEMSdevice that is applied to an optical switch and a light modulationdevice by taking advantage of the reflection or diffraction of light.

[0005] An optical MEMS device 1 shown in FIG. 13 includes a substrate 2,a substrate side electrode 3 formed on the substrate 2, a beam 6 havinga driving side electrode 4 that is disposed in parallel to oppose thesubstrate side electrode 3, and a support part 7 for supporting one endof the beam 6. The beam 6 and substrate side electrode 3 areelectrically insulated by a void 8 therebetween.

[0006] A required substrate such as a substrate with an insulation filmformed on a semiconductor substrate of, for example, silicon (Si),gallium arsenic (GaAs) and the like, or an insulative substrate such asa glass substrate is used for the substrate 2. The substrate sideelectrode 3 is formed of a polycrystalline silicon film by dopingimpurities therein, metal film (Cr deposited film, for example), and thelike. The beam 6 is composed of, for example, an insulation film 5 suchas silicon nitride film (SiN film) or the like and the driving sideelectrode 4 serving as a reflective film consisting of, for example, Alfilm of 100 nm or so in thickness. The beam 6 is formed in a so-calledcantilever fashion with its one end supported by the support part 7.

[0007] In the optical MEMS device 1, the beam 6 displaces itself inresponse to electrostatic attraction force or electrostatic repulsionforce generated between the substrate side electrode 3 and driving sideelectrode 4 by an electric potential that is applied to the substrateside electrode 3 and driving side electrode 4, and as shown by a solidline as well as a broken line in FIG. 13, for example, the beam 6displaces itself into a parallel state or inclined state relative to thesubstrate side electrode 3.

[0008] An optical MEMS device 11 shown in FIG. 14 is composed of asubstrate 12, a substrate side electrode 13 formed on the substrate 12and a beam 14 that straddles the substrate side electrode 13 in abridge-like fashion. The beam 14 and substrate side electrode 13 areinsulated by a void 10 therebetween.

[0009] The beam 14 is composed of a bridge member 15 of, for example, aSiN film that rises up from the substrate 12 and straddles a substrateside electrode 13 in a bridge-like fashion and a driving side electrode16 of, for example, an Al film of 100 nm or so in thickness that,serving as a reflective film, is provided on the bridge member 15 tooppose the substrate side electrode 13 in parallel to each other. Thesubstrate 12, substrate side electrode 13, beam 14 and the like mayemploy similar compositions and materials to those explained in FIG. 13.The beam 14 is formed in a so-called bridge-like fashion in which theboth ends thereof are supported.

[0010] In the optical MEMS device 11, the beam 14 displaces itself inresponse to electrostatic attraction force or electrostatic repulsionforce generated between the substrate side electrode 13 and driving sideelectrode 16 by an electric potential that is applied to the substrateside electrode 13 and driving side electrode 16, and as shown by a solidline and a broken line as well in FIG. 14, for example, the beam 14displaces itself into a parallel state or fallen state relative to thesubstrate side electrode 13.

[0011] With these optical MEMS devices 1, 11, light is irradiated on thesurfaces of the driving side electrodes 4, 16 serving as a lightreflective film, and by taking advantage of differences in the directionof reflected light depending upon positions into which the beams 6, 14are driven, these MEMS devices can be applied to an optical switchhaving a switch function by detecting the reflected light of onedirection.

[0012] Further, the optical MEMS devices 1, 11 are applicable as a lightmodulation device for modulating the strength of light. When lightreflection is taken advantage of, the strength of light is modulated byvibrating the beams 6, 14 according to the amount of reflected light inone direction per unit time. This light modulation device runs on aso-called time modulation.

[0013] When light diffraction is taken advantage of, a light modulationdevice is composed of a plurality of beams 6, 14 disposed in parallelrelative to the common substrate side electrodes 3, 13, and by varyingthe height of, for example, driving side electrodes serving as a lightreflective film with the movements of every other beam 6, 14 such asmoving closer to or moving away from the common substrate sideelectrodes 3, 13, the strength of reflected light from the driving sideelectrodes is modulated by means of light diffraction. This lightmodulation device runs on a so-called space modulation.

[0014]FIG. 15 shows a composition of the GLV (Grating Light Valve)device developed by SLM (Silicon Light Machines) as a light strengthmodulation device for a laser display, that is, a light modulator.

[0015] In a GLV device 21, as shown in FIG. 15A, a common substrate sideelectrode 23 of a refractory metal, for example, tungsten or titaniumfilm or a nitride film thereof, or of a poly-silicon thin film is formedon an insulation substrate 22 such as a glass substrate or the like, anda plurality of beams 24, in this example, six beams [24 ₁, 24 ₂, 24 ₃,24 ₄, 24 ₅, 24 ₆] straddling across the substrate side electrode 23 in abridge-like fashion are disposed in parallel. The compositions of thesubstrate side electrode 23 and beams 24 are the same as those explainedin FIG. 14. Namely, as shown in FIG. 15B, a reflective film cum drivingside electrode 26 of an Al film of 100 nm or so in thickness is formedon the surface, which is in parallel to the substrate side electrode 23,of a bridge member 25 of a SiN film, for example.

[0016] The beam 24 composed of the bridge member 25 and reflective filmcum driving side electrode 26 provided thereon is a portionconventionally called a ribbon.

[0017] The aluminum film (Al film) used as the reflective film cumdriving side electrode 26 is a suitable metal as the material foroptical components because of the following reasons: (1) it is a metalthat can be comparatively easily formed into a film; (2) the dispersionof reflectance with respect to wavelengths in a visible light range issmall; (3) alumina natural oxidation film generated on the surface ofthe Al film functions as a protective film to protect a reflectivesurface.

[0018] Further, the SiN film (silicon nitride film) composing the bridgemember 25 is formed by the use of the low-pressure CVD method, and theSiN film is selected by reason of the physical values of its strength,elasticity constant, and the like being suitable for mechanicallydriving the bridge member 25.

[0019] When a voltage is applied between the substrate side electrode 23and reflective film cum driving side electrode 26, the above-mentionedbeam 24 moves closer to the substrate side electrode 23 according to theabove-mentioned electrostatic phenomenon, and when the application ofthe voltage is stopped, the beam 24 moves away from the substrate sideelectrode 23 and returns to an original position.

[0020] The GLV device 21 alternately varies the height of the reflectivefilm cum driving side electrode 26 with the movements of the pluralityof beams 24 such as moving closer to or moving away from the substrateside electrode 23 (that is, those movements of every other beams), andmodulates the strength of light reflected on the driving side electrode26 by means of the diffraction of light (one beam spot is irradiated onthe whole of six beams 24).

[0021] Mechanical characteristics of the beam driven by taking advantageof electrostatic attraction force and electrostatic repulsion force arealmost predicated on the physical properties of the SiN film formed bythe use of the CVD method or the like, with an Al film mainlyfunctioning as a mirror.

[0022] By the way, as described above, the substrate side electrode inthe MEMS device is formed on an insulation layer of a semiconductorsubstrate made of silicon, GaAs, or the like, or an insulative substratesuch as a glass substrate or the like. As for materials of theelectrode, a polycrystalline silicon film or metal film, in whichimpurities are doped is used. However, since these materials have acrystalline structure, there occurs unevenness on the surface thereof.For example, in the case of a polycrystalline silicon electrode,according to an analysis by AFM (an atomic force microscope),controlling relative roughness RMS (root mean square) value of a surfacecan be achieved by strictly carrying out temperature control in themanufacturing process, and it is a well known fact that there easilyoccurs surface relative roughness of 20 nm or more after an conventionalfilm forming process and a semiconductor manufacturing process that haveso far been practiced. The degree of the roughness depends on materialsand film forming methods as well.

[0023] This surface unevenness poses not so serious a problem in termsof the electric characteristics as well as the operating characteristicsof the MEMS device, but it often has become problems in themanufacturing process of an optical MEMS device. Namely, the substrateside electrode of the above-mentioned MEMS device is usually positionedunder the reflective film cum driving side electrode. In this case,surface unevenness of a lower layer film becomes sequentiallytranscribed to an upper layer film in the manufacturing process, therebyresulting in the forming of a driving side electrode with piled-uptranscribed surface unevenness, that is, the forming of a reflectivefilm therewith on the uppermost layer that is an optically importantfilm surface.

[0024] For example, the MEMS device 1 mentioned above in FIG. 13 ismanufactured in such a manner that the substrate side electrode 3 isformed on a substrate, and after forming the support part 7, asacrificial layer (not shown) to form a void is provided on a surfaceincluding the substrate side electrode 3, and further, a beam is formedon the sacrificial layer, followed by forming a void 8 between thesubstrate side electrode 3 and the beam 6 by removing the sacrificiallayer. Silicon (polycrystalline silicon, non-crystalline silicon, or thelike) or a silicon oxide film is used for the sacrificial layer. Whenthe sacrificial layer is made of silicon, it can be removed by, forexample, a mixture of nitric acid and fluoric acid, or gas etchingemploying a gas containing fluorine (F), and when the sacrificial layeris made of an oxidized layer, it is conventionally removed by an oxygenfluoride solution, or by etching employing fluorinated carbon gas.

[0025] That is, with the optical MEMS device that is manufactured to becomposed of three layers of: a substrate side electrode (a), voidforming a sacrificial layer (b), and a reflective film cum driving sideelectrode (c), assuming that the maximum values of surface unevennessthat are observed in each of the respective layers are R_(max) (a),R_(max) (b), R_(max) (c), there is a possibility that when the threelayers are laminated, the amount of surface unevenness on the surface ofthe uppermost layer adds up to the sum of these maximum values.

[0026] Expressing the performance of optical components, in the MEMSdevice, in which aluminum (Al) is made to serve as a reflective film,92% of reflectance of the Al film may possibly be obtained if the filmis a bulk Al film. However, if there is no control on the amount of thissurface unevenness, the reflectance will deteriorate by more thanseveral percentage points, so that only 85% or so thereof can barely beobtained. In an extreme case, it is observed that the surface appears tobe clouded up. Such an optical MEMS device becomes a problem when itsperformance as a optical device is concerned.

[0027] Further, there remains a problem concerning design. While a MEMStransducer, that is, the resonant frequency of a beam is designed bytaking account of the mass of resonance, the tensile force of films inrespective regions that support the driving part, and the like, in thepresent circumstances the values of physicality of the respective filmsare conventionally computed and designed by using the values ofphysicality where films are in an ideal thin state. However, when a RMSvalue is 20 nm, for example, and the thickness of a film for use becomessmaller in comparison therewith, it becomes impossible to disregard aswell from the standpoint of a film structure, thereby necessitating aredesign for a MEMS device, including a mechanical modification of theswell structure thereof, which is extremely difficult to achieve bymeans of tools for design that are available in the circumstances, whencomputing time and the accuracy of the tools are taken into account.

[0028] As shown in FIG. 16, when the substrate side electrode is formedof, for example, polycrystalline silicon, surface unevenness is expandedand transcribed onto the surface of the driving side electrode (Al film)4 that constitutes the beam (Al/SiN laminated layer) 6, resulting in thedeterioration of the light reflectance of the driving side electrode 4functioning as a mirror.

[0029] Meanwhile, the MEMS device has a packaging process, as shown inFIGS. 17A and 17B, for the purpose of protecting the beam serving as anoperating part. In this packaging process, there is formed a columnarsupport part 18 formed of, for example, an oxidized silicon layer on thesubstrate 2, and a transparent substrate, for example, a glass substrate9 is joined onto the columnar support part 18. Since a power supplyingwiring 10 for driving the MEMS device 1 is formed at the same time asthe substrate 3 is formed, a part of the columnar support part 18 takesthe form of creeping over the wiring 10, so that stepped differencesoccur on the surface of the part of columnar support part 18 due to thewiring 10. Consequently, the glass substrate 9 of a package member isunable to be placed in close contact with the overall surface of thecolumnar support part 18, and surface unevenness is transcribed to asurface 18 a of the columnar support part, which becomes an obstaclewhen the surface 18 a of the columnar support part 18 is joined with theglass substrate 9 by means of, for example, the anode bonding method.

DISCLOSURE OF THE INVENTION

[0030] The present invention provides an electrostatic drive type MEMSdevice which aims at flattening the surface of a beam, improving itsperformance, and further improving the degree of freedom of designing,and manufacturing methods thereof, an optical MEMS device, an opticalmodulation device, GLV device, and laser display.

[0031] An electrostatic drive type MEMS device according to the presentinvention is composed of a substrate side electrode and a beam that isdisposed to oppose the substrate side electrode and has a driving sideelectrode driven by electrostatic attraction force or electrostaticrepulsion force that acts between the substrate side electrode anddriving side electrode, with the substrate side electrode being formedof an impurities-doped conductive semiconductor region in asemiconductor substrate. The conductive semiconductor region can beformed to be electrically insulated from the peripheral region of thesemiconductor substrate by being insulated and isolated by means ofselective oxidation or trench isolation.

[0032] A manufacturing method of the electrostatic drive type MEMSdevice according to the present invention has the processes of: forminga substrate side electrode that is insulated to be isolated from otherparts by doping impurities onto the surface of a semiconductorsubstrate, selectively forming a sacrificial layer including the upperpart of the substrate side electrode, forming on the sacrificial layer abeam having a driving side electrode, and removing the sacrificiallayer. The doping of the impurities is carried out by means of an ioninjection method, a thermal diffusion method or a solid phase diffusionmethod.

[0033] With the electrostatic drive type MEMS device according to thepresent invention, since a substrate side electrode is formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate, the surface of the semiconductor substrate is maintained asthe surface of the substrate side electrode as it is and is maintainedas an extremely flattened one by a mirror finish. Therefore, the surfaceof the beam, which opposes the substrate side electrode, ultimatelyobtained by sequentially laminating a sacrificial layer, beam and thelike on the substrate side electrode, and the surface of a driving sideelectrode are flattened. When the driving side electrode is used as alight reflective film, light reflectance on the surface of the drivingside electrode is improved.

[0034] According to the manufacturing method of an electrostatic drivetype MEMS device of the present invention, it is possible to easily andaccurately manufacture the MEMS device having a beam, the surface ofwhich is flattened.

[0035] An optical MEMS device according to the present invention iscomposed of a substrate side electrode, a beam that is disposed tooppose the substrate side electrode and has a light reflective film cumdriving side electrode driven by electrostatic attraction force orelectrostatic repulsion force acting between the substrate sideelectrode and driving side electrode, with the substrate side electrodebeing formed of the impurities-doped conductive semiconductor region inthe semiconductor substrate.

[0036] With the optical MEMS device according to the present invention,since a substrate side electrode is formed of an impurities-dopedconductive semiconductor region in the semiconductor substrate, thesurface of the semiconductor substrate is maintained as the surface ofthe substrate side electrode as it is and is maintained as an extremelyflattened one by a mirror finish. Therefore, as described above, theultimately obtained surface, which reflects light, of a light reflectivefilm cum driving side electrode of a beam is flattened, therebyimproving light reflectance as well as light use efficiency.

[0037] A light modulation device according to the present invention iscomposed of a substrate side electrode, a beam that is disposed tooppose the substrate side electrode and has a light reflective film cumdriving side electrode driven by electrostatic attraction force orelectrostatic repulsion force acting between the substrate sideelectrode and the driving side electrode, with the substrate sideelectrode being formed of an impurities-doped conductive semiconductorregion in a semiconductor substrate.

[0038] With the light modulation device according to the presentinvention, since a substrate side electrode is formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate, the surface of the semiconductor substrate is maintained asthe surface of the substrate side electrode as it is and is maintainedas an extremely flattened surface by a mirror finish. Therefore, as wasdescribed above, the degree of flatness of the ultimately obtainedsurface, which reflects light, of a light reflective film cum drivingside electrode of a beam is remarkably improved, thereby improving lightreflectance as well as light use efficiency.

[0039] A GLV device according to the present invention is composed of acommon substrate side electrode, a plurality of beams that are disposedto oppose the common substrate side electrode and have a lightreflective film cum driving side electrodes driven by electrostaticattraction force or electrostatic repulsion force acting between thesubstrate side electrode and the driving side electrodes, with thesubstrate side electrode being formed of a impurities-doped conductivesemiconductor region in the semiconductor substrate.

[0040] With the GLV device according to the present invention, since asubstrate side electrode is formed of an impurities-doped conductivesemiconductor region in a semiconductor substrate, the surface of thesemiconductor substrate is maintained as the surface of the substrateside electrode as it is and is maintained as an extremely flattenedsurface by a mirror finish. Therefore, as described above, theultimately obtained surface, which reflects light, of a light reflectivefilm cum driving side electrode of a beam is flattened, therebyimproving light reflectance as well as light use efficiency.

[0041] A laser display according to the present invention includes alaser light source, and a GLV device which is disposed on the opticalaxis of a laser beam emitted from the laser light source and modulatesthe strength of laser beams, wherein the GLV device is composed ofcommon substrate side electrodes, and a plurality of beams that aredisposed to oppose the common substrate side electrodes and have lightreflective film cum driving side electrodes driven by electrostaticattraction force or electrostatic repulsion force acting between thesubstrate side electrode and the driving side electrodes, with thesubstrate side electrode being formed of an impurities-doped conductivesemiconductor region in a semiconductor substrate.

[0042] With the laser display of the present invention, since in a GLVdevice that modulates the strength of a laser beam a substrate sideelectrode is formed of an impurities-doped conductive semiconductorregion, as described above, the surfaces of light reflective film cumdriving side electrodes of a plurality of beams are flattened.Therefore, light reflectance increases, and light use efficiency in thelaser display improves.

[0043] According to an electrostatic drive type MEMS device of thepresent invention, since a substrate side electrode is formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate, and the surface of the substrate side electrode is maintainedas the same flattened surface as the surface of the semiconductorsubstrate, surface unevenness (roughness) of a driving side electrode ofa beam, which has become obvious in the MEMS device, can be extremelyreduced and flattened as well. As a result, improvements in theperformance of the MEMS device can be obtained. Further, since thesubstrate side electrode of the MEMS device is formed on the samesurface as the surface of the semiconductor substrate, the flatness ofan overall chip having the MEMS device is improved, the degree offreedom of packaging that is unique to the MEMS device is increased, thedegree of freedom in designing a manufacturing process can be improved,and reduction of costs can be implemented.

[0044] According to manufacturing methods of an electrostatic drive typeMEMS device of the present invention, it is possible to manufacture theabove-mentioned MEMS devices easily and accurately.

[0045] When an electrostatic drive type MEMS device of the presentinvention is applied to an optical MEMS device, since the surface of alight reflective film cum driving side electrode is flattened, lightreflectance improves, light use efficiency increases, and improvementsin the performance of the MEMS device can be implemented.

[0046] When an electrostatic drive type MEMS device of the presentinvention is applied to a light modulation device that takes advantageof light reflection or light diffraction, since the surface of a lightreflective film cum driving side electrode is flattened, lightreflectance improves, and it is possible to provide the light modulationdevice with high light-use efficiency. That is, the light modulationdevice with improved performance can be provided.

[0047] When a GLV device is composed of a light modulation device of thepresent invention, it is possible to provide the GLV device with highlight-use efficiency. That is, the GLV device with improved performancecan be provided.

[0048] When a GLV device of the present invention is incorporated in alaser display, it is possible to provide the laser display with highlight-use efficiency. That is, the laser display with improvedperformance can be provided.

BRIEF DESCRIPTION OF DRAWINGS

[0049]FIG. 1 is a diagram showing a typical embodiment of anelectrostatic drive type MEMS device according to the present invention;

[0050]FIG. 2A is one example of a region insulated to be isolated of asubstrate side electrode of the electrostatic drive type MEMS deviceaccording to the present invention, and FIG. 2B is another example ofthe region insulated to be isolated of the substrate side electrode ofthe electrostatic drive type MEMS device of the present invention;

[0051]FIG. 3 is a diagram showing another typical embodiment of theelectrostatic drive type MEMS device according to the present invention;

[0052]FIG. 4 is a diagram showing a further another typical embodimentof the electrostatic drive type MEMS device according to the presentinvention;

[0053]FIG. 5 is a cross-sectional view of a relevant part of a drivingside electrode of the electrostatic drive type MEMS device according tothe present invention;

[0054]FIGS. 6A to 6C are diagrams showing one embodiment of amanufacturing process (first sequence) of a manufacturing method of theelectrostatic drive type MEMS device of FIG. 1;

[0055]FIGS. 7A and 7B are diagrams showing one embodiment of amanufacturing process (second sequence) of the manufacturing method ofthe electrostatic drive type MEMS device of FIG. 1;

[0056]FIGS. 8A to 8C are diagrams showing another embodiment of amanufacturing process (first sequence) of the manufacturing method ofthe electrostatic drive type MEMS device of FIG. 1;

[0057]FIGS. 9A and 9B are diagrams showing another embodiment of amanufacturing process (second sequence) of the manufacturing method ofthe electrostatic drive type MEMS device of FIG. 1;

[0058]FIG. 10A is a structural diagram of a relevant part of a packageof the MEMS device, and FIG. 10B is a structural diagram of a relevantpart of FIG. 8A seen from the direction at an angle of 90° thereof;

[0059]FIG. 11A is a structural diagram showing an embodiment of a GLVdevice according to the present invention, and FIG. 11B is across-sectional view of FIG. 11A;

[0060]FIG. 12 is a block diagram showing an embodiment of a laserdisplay according to the present invention;

[0061]FIG. 13 is one typical example of an optical MEMS device offeredfor explaining a conventional one;

[0062]FIG. 14 is another typical example of the optical MEMS deviceoffered for explaining a conventional one;

[0063]FIG. 15 is a structural diagram showing a conventional GLV device;

[0064]FIG. 16 is a cross-sectional view of a relevant part showingunevenness of a driving side electrode of a conventional optical MEMSdevice; and

[0065]FIG. 17A is a structural diagram of a relevant part of a packageof a conventional MEMS device, and FIG. 17B is a structural diagram ofthe relevant part of FIG. 17A seen at an angle of 90° thereof.

BEST MODE FOR CARRYING OUT THE INVENTION

[0066] Hereinafter, the embodiments of the present invention will beexplained with reference to drawings.

[0067]FIG. 1 shows one typical embodiment of an electrostatic drive typeMEMS device according to the present invention.

[0068] A MEMS device 31 according to the present invention is composedby forming a conductive semiconductor region 33 in a predeterminedregion of one surface of a semiconductor substrate 32 with the requiringdoping of impurities of a conductive type, and after the conductivesemiconductor region 33 is made to be a substrate side electrode, bydisposing an electrostatic drive type beam 35, one end of which issupported by an insulative support part 34 so as to oppose the substrateside electrode 33. The beam 35 is composed in a so-called cantileverfashion. Meanwhile, a semiconductor integrated circuit and the like tocontrol the driving is incorporated into a part of the MEMS device 31.

[0069] A substrate consisting of, for example, silicon (Si), galliumarsenic (GaAs) or the like can be used as the semiconductor substrate32. By doping impurities of a p type or n type into the semiconductorsubstrate 32 by means of the ion implantation method, thermal diffusionmethod, or solid phase diffusion method, a conductive semiconductorregion, that is, the substrate side electrode 33 can be formed. Thesubstrate side electrode 33 is insulated to be isolated from theperiphery by an isolating-by-insulation region 36.

[0070] As for the isolation by insulating the substrate side electrode33, as shown in FIG. 2A, a selective oxidation (so-called LOCOS) layer36 ₁ is formed on the surface of, for example, the silicon semiconductorsubstrate 32, by which the substrate side electrode 33 can be insulatedto be isolated.

[0071] Alternatively, as shown in FIG. 2B, the substrate side electrode33 can be insulated to be isolated by trench isolation (STI: ShallowTrench Isolation). Namely, a trench 43 is formed to surround theconductive semiconductor region 33, and the substrate side electrode 33can be insulated to be isolated by a trench isolation region 362 that isformed by embedding an insulating layer, for example, a silicon oxidelayer 44 in the trench 43.

[0072] The insulative support part 34 can be formed of an insulatingbody: such as a silicon nitride (SiN) film, silicon oxide film (SiO₂),in this embodiment, the silicon nitride film. The beam 35 can be formedof an insulation film, such as a silicon nitride (SiN) film, siliconoxide film (SiO₂), in this embodiment, a laminated film of the siliconnitride film (SiN) 37, and a driving side electrode 38 thereon, physicalproperty values of which such as strength, elastic constant and the likeare suitable for mechanically driving the beam. As for the driving sideelectrode 38, an Ag film, an Al film mainly consisting of aluminum (Al),a refractory metal film formed of any one of titanium (Ti), tungsten W,molybdenum Mo, tantalum Ta or the like can be employed.

[0073]FIGS. 6 and 7 show one embodiment of the manufacturing method ofthe above-mentioned electrostatic drive type MEMS device 31.

[0074] First, as shown in FIG. 6A, the insulation layer 36, is formed ina predetermined region on one surface of a semiconductor substrate, forexample, silicon mono-crystalline substrate 32 through selectiveoxidation (LOCOS), and impurities of a p type or n type are doped in aregion surrounded by the insulation layer 36 ₁ to form the conductivesemiconductor region (so-called impurities diffused region) 33. Theconductive semiconductor region 33 becomes a substrate side electrode.

[0075] As the method for doping impurities to form the conductivesemiconductor region 33, there are the ion injecting method, thermaldiffusion method, solid phase diffusion method and the like. In the caseof the ion injecting method, accelerated phosphor, boron, arsenic or thelike is doped in the silicon substrate 32, and heat treatment is appliedthereto so as to restore the crystallinity of the silicon substrate 32.With the thermal diffusion method, at a time of phosphor being doped,heat treatment is performed in an atmosphere of CL₃PO gas. With thesolid phase diffusion method, a boron silicate glass (BSG) film inwhich, for example, phosphor is doped, a phosphor silicate glass (PSG)film in which boron is doped or the like is laminated on the siliconsubstrate 32, and after heat treatment is applied thereto, followed bysolid phase diffusion, impurities such as boron or phosphor are dopedtherein.

[0076] Next, as shown in FIG. 6B, an insulation film serving as acolumnar support part, in this embodiment, silicon nitride film isformed on the upper surface of the silicon substrate 32 with the CVDmethod or the like, and patterning is performed thereto to form thecolumnar support part 34 formed of a silicon nitride film at a positiondetached from the substrate side electrode 33. Next, a sacrificial layerfor forming a void, in this embodiment, polycrystalline silicon film 40is formed on the whole surface, followed by etching the polycrystallinesilicon layer 40 so that the surface becomes flush with the surface ofthe columnar support part 34. In addition, other than thepolycrystalline film, a non-crystalline silicon film, a photoresist filmor an insulation film (for example, silicon oxide film, silicon nitridefilm or the like) that has an etching rate different from that of theinsulation film constituting the columnar support part 34 and beam canbe used as the sacrificial layer 40.

[0077] Next, as shown in FIG. 6C, an insulation film, for example, suchas the silicon nitride film, silicon oxide film or the like, in thisembodiment, a silicon nitride film 37, and a driving side electrodematerial layer 38′ thereupon are sequentially laminated on the overallsurface that includes the upper surface of the columnar support part 34and polycrystalline silicon layer 40.

[0078] Next, as shown in FIG. 7A, a resist mask 41 is formed, followedby selectively removing a driving side electrode material layer 38′ andthe silicon nitride film 37 thereunder by etching through the resistmask 41 so as to form the beam 35 that is composed of the driving sideelectrode 38 and silicon nitride film 37, which is supported by thecolumnar support part 34.

[0079] Next, as shown in FIG. 7B, the polycrystalline silicon layer 40constituting the sacrificial layer is removed by etching with, forexample, a XeF₂ gas to form a void 40 between the substrate sideelectrode 33 and beam 35 to resultantly obtain the targetedelectrostatic drive type MEMS device 31.

[0080]FIGS. 8 and 9 show another embodiment of the manufacturing methodof the above-mentioned electrostatic drive type MEMS device 31.

[0081] First, similarly to FIG. 6A mentioned above, as shown in FIG. 8A,the insulation layer 36, is formed by selective oxidation (LOCOS) in apredetermined region on one surface of a semiconductor substrate, forexample, the silicon mono-crystalline substrate 32, followed by dopingimpurities of a p type or n type in the region surrounded by theinsulation layer 36 ₁ to form the conductive semiconductor region(so-called impurities diffused region) 33. The conductive semiconductorregion 33 becomes a substrate side electrode.

[0082] Next, as shown in FIG. 8B, a sacrificial layer, for example, apolycrystalline silicon film 50 is laminated over the overall surface ofthis substrate, that is, the substrate 32 in which impurities diffusedregion 33 are partly formed.

[0083] Next, as shown in FIG. 8C, an opening 51 serving as a post(columnar support part) to support the beam is formed in a region of thepolycrystalline silicon film 50.

[0084] Next, as shown in FIG. 9A, a laminated film of, for example, theSiN film 37 and Al film 38′ which serves as the beam is formed on thepolycrystalline silicon film 50 constituting the sacrificial layer,including the inside of the opening 51. The two-layer film (37, 38′) ofAl/SiN that is formed on the side walls of the opening 51 becomes a postto support the beam 52, which is a cylinder or square column in shapewith its core hollowing out.

[0085] Finally, as shown in FIG. 9B, the Al/SiN laminated film (37, 38′)is processed to form a predetermined pattern, and the beam 35 composedof the SiN film 37 and driving side electrode 38 consisting of Al isformed, with the result that the targeted MEMS device 31 is obtained. InFIG. 9B, since the beam 35 is elongated toward one direction from thepost 52, the MEMS structured in a cantilever beam fashion can beobtained.

[0086] According to the manufacturing method of the MEMS device 31 ofthis embodiment, since the substrate side electrode 33 is formed of theconductive semiconductor region (impurities diffused region) formed onone surface of the silicon mono-crystalline substrate 32, the siliconmono-crystalline substrate 32 is maintained as the surface of thesubstrate side electrode 33 as it is so that the surface thereof ismaintained as an extremely flat one with a polished mirror finish.Therefore, in the manufacturing process, when the sacrificial layer 40,and the SiN film 37 and driving side electrode 38 constituting beam 35are sequentially laminated on the substrate side electrode 33, theunevenness of layers underlaid shown in FIG. 16 as mentioned above isnot reflected, so that an upper surface 38 a of the driving sideelectrode 38 of the beam 35 and the bottom surface of the insulationfilm 37 of the beam 35 opposing the substrate side electrode 33 can beflattened. Particularly, a surface only affected by unevenness due tocrystal grains of the film composing the driving side electrode 38 isobtained as the upper surface 38 a. When, for example, the driving sideelectrode 38 is formed of an Al film, the upper surface of the Al filmis affected only by the unevenness of crystal grains of the Al film. Asa result, as shown in FIG. 5, the driving side electrode 38 withexcellent flatness is obtained.

[0087] When the MEMS device 31 is applied to an optical MEMS device, theupper surface 38 a of the driving side electrode 38 becomes a flattenedlight reflective surface (so-called mirror surface), which improveslight reflectance and increases the light use efficiency of reflectedlight, making it possible to implement improvements in the performanceof the optical devices such as a light switch capable of controllingon-off, the light modulation device for modulating the strength oflight, and the like.

[0088] According to the manufacturing method of the MEMS deviceaccording to this embodiment, since the substrate side electrode 33 isformed of the impurities diffused region formed by doping impurities inthe semiconductor substrate 32, the surface of the mono-crystallinesubstrate 32 is maintained as the surface of the substrate sideelectrode 33 as it is, resulting in a flat surface having a polishedmirror finish. Subsequently, the sacrificial layer 40 or 50, insulationlayer 37 and driving side electrode material layer 38′ are sequentiallylaminated, followed by removing the sacrificial layer 40 or 50. As aresult, it becomes possible to manufacture precisely and easily the MEMSdevice 31 having the beam 35 in which the driving side electrode 38 isflattened.

[0089]FIG. 3 shows another typical embodiment of the electrostatic drivetype MEMS device according to the present invention. This embodimentshows the case in which the beam is formed in a bridge-like fashion.

[0090] A MEMS device 51 according to the embodiment is composed suchthat the conductive semiconductor region 33 is formed by dopingimpurities of a required conductive type in a predetermined region ofone surface of the semiconductor substrate 32, and with the conductivesemiconductor region 33 serving as a substrate side electrode, a beam 52of an electrostatic drive type is disposed to oppose the substrate sideelectrode 33 so as to straddle the substrate side electrode 33 in abridge-like fashion. The substrate side electrode 33 is insulated to beisolated from the periphery by the isolating-by-insulation region 36such as the insulation layer 36, by the use of selective oxidation, thetrench isolation region 362 or the like, respectively shown in FIGS. 2A,2B as mentioned above.

[0091] The beam 52 is composed of an insulation film rising up from thesubstrate 32 so as to straddle the substrate side electrode 33 in abridge-like fashion, for example, bridge member 53 of, for example,silicon nitride (SiN) film, and a driving side electrode 54 provided onthe bridge member 53, which opposes the substrate side electrode 33, tobe in parallel to each other.

[0092] Since the semiconductor substrate 32, substrate side electrode33, the insulation film 53 and driving side electrode 54 composing beam52, and the like can employ the same composition and materials explainedin FIG. 1, detailed explanations will be omitted.

[0093] The MEMS device 51 can be manufactured by the same processes asexplained above in FIGS. 6 and 7.

[0094] Namely, after the substrate side electrode 33 composed of theconductive semiconductor region (impurities diffused region) is formedby doping impurities onto the surface of the region surrounded by theisolating-by-insulation region 36 of the semiconductor substrate 32, thesacrificial layer is formed selectively, including the upper part of thesubstrate side electrode 33; followed by forming the bridge-likeinsulation film 53, including an upper part of the sacrificial layer andthat of the substrate where the isolated-by-insulation region is formed,and by forming the driving side electrode 54 on the surface, which is inparallel to the substrate side electrode 33, of the bridge-likeinsulation film 53, to thereby form the beam 52, and thereafter, byremoving the sacrificial layer, the MEMS device 51 can be manufactured.

[0095] As with the electrostatic driving type MEMS device 51 accordingto this embodiment, the same as was mentioned above, since the substrateside electrode 33 is composed of the conductive semiconductor region(impurities diffused region) formed on one surface of the siliconmono-crystalline substrate 32, the unevenness of the surfaces underlaidis not reflected onto an upper surface 54 a of the driving sideelectrode 54 of the beam 52, which becomes the surface only affected bythe unevenness due to crystal grains of a film composing the drivingside electrode 54 and is flattened. Therefore, when the electrostaticdriving type MEMS device 51 is applied to an optical MEMS device, theupper surface 54 a of the driving side electrode 54 becomes a moreflattened mirror surface to improve light reflectance and increasereflected light use efficiency, thereby enabling the performance of thelight switch, light modulation device and the like as optical devices tobe improved.

[0096]FIG. 4 shows another typical embodiment of the electrostatic drivetype MEMS device according to the present invention.

[0097] A MEMS device 55 according to the present invention is composedsuch that impurities of a required conductive type are doped in apredetermined region of one surface of the semiconductor substrate 32,for example, two regions opposing across the center thereof to formconductive semiconductor regions 33 [33A, 33B], and by the conductivesemiconductor regions 33A, 33B each being made to be substrate sideelectrodes, beams 56 [56A, 56B] are disposed so as to oppose the bothsubstrate side electrodes 33A, 33B, respectively. The beams 56A, 56B areformed of a common beam, and composed of parts that extend in the rightand left directions from the central part of the beams, which aresupported by a support part 57. The substrate side electrodes 33A, 33Bare insulated to be isolated from the periphery by the sameisolating-by-insulation region 36 mentioned above. The beam 56 is formedof a laminated film of an insulation film, for example, a siliconnitride (SiN) film 58 and a driving side electrode 59 thereupon.

[0098] Since the semiconductor substrate 32, the substrate sideelectrodes 33 [33A, 33B], the insulation film 58 composing the beams 56[56A, 56B], the driving side electrode 59 and the like can employ thesame composition and materials as explained above in FIG. 1, detailedexplanations will be omitted.

[0099] Further, though the substrate side electrodes 33A, 33B are formedindependently, there can be a composition in which the beams 56A, 56Bare disposed so as to oppose the substrate side electrode 33 as the onecommon substrate side electrode 33.

[0100] The MEMS device 55 can be manufactured by the same processes asexplained above in FIGS. 6 and 7.

[0101] Namely, the MEMS device 55 can be manufactured such that thesubstrate side electrodes 33 [33A, 33B] composed of the conductivesemiconductor regions (impurities diffused regions) are formed by dopingimpurities onto the surface of the region surrounded by theisolating-by-insulation region 36 of the semiconductor substrate 32, andafter selectively forming in a central part the support part 57 composedof an insulation film, a sacrificial layer is selectively formedincluding the upper part of the substrate side electrodes 33 [33A, 33B],followed by forming the insulation film 58 and driving side electrode 59including the upper surfaces of the support part 57 and sacrificiallayer to thereby form the beams 56 [56A, 56B], and thereafter, thesacrificial layer is removed to obtain the MEMS device 55.

[0102] As with the electrostatic driving type MEMS device 55, the sameas was mentioned above, since the substrate side electrodes 33 [33A,33B] are composed of the conductive semiconductor regions (impuritiesdiffused regions) formed on one surface of the silicon mono-crystallinesubstrate 32, the unevenness of the surfaces underlaid is not reflectedonto the surface of the driving side electrode 59 of the beams 56 [56A,56B], which becomes the surface only affected by the unevenness due tocrystal grains of a film composing the driving side electrode 59 and isflattened. Therefore, when the electrostatic driving side type MEMSdevice 55 is applied to the optical MEMS device, the upper surface 56 aof the driving side electrode 56 becomes a more flattened mirror surfaceto thereby improve light reflectance and increase reflected light useefficiency, enabling the performance of the light switch, lightmodulation device and the like as optical devices to be improved.

[0103] The above-mentioned MEMS devices 31, 51, 55 can be applied to anoptical MEMS device that takes advantage of light reflection, and anoptical MEMS device that takes advantage of light diffraction. In thecase of taking advantage of the light reflection, it is possible toemploy a composition wherein one beam 35, 52 or 56 is disposed so as tooppose the substrate side electrode 33, or a composition wherein aplurality of beams 35 each drive independently so as to oppose thecommon substrate side electrode 33. In the case of taking advantage ofthe light diffraction, the optical MEMS device is composed of aplurality of beams 35, 52 or 56 disposed in parallel.

[0104] It is possible to compose a light modulation device by the use ofthe above-mentioned optical MEMS device.

[0105] According to the light modulation device of the embodiments,since reflection efficiency and diffraction efficiency improve,reflected-light using ratio is improved and characteristics andperformance as the light modulation device can be improved.

[0106] FIGS 10A and 10B show the composition of a package for protectingthe MEMS device.

[0107] According to this embodiment, the substrate side electrode 33 iscomposed of the conductive semiconductor region that is formed by dopingimpurities in the semiconductor substrate 32, and at the same time, apower supplying wiring 44 for driving the MEMS device 31 is alsocomposed of the conductive semiconductor region that is formed by dopingimpurities in the same semiconductor substrate 32 as in the case of thesubstrate side electrode 33. Columnar support parts 45 are formed so asto surround the MEMS device 31 (specifically, beam 35, driving body partincluding substrate side electrode 33) of, for example, a SiO₂ layer onthe substrate 32. Although a part of the columnar support part 45 isformed so as to creep over the wiring 44, the surface of the columnarsupport part 45 is formed into a flat surface across the overall surfacethereof without stepped differences, because the substrate sideelectrode 33 is composed of the conductive semiconductor region(impurities diffused region) in the semiconductor substrate 32. Further,there is no unevenness on the surface of the wiring 44, so that theunevenness on the surface of the conventional wiring is not transcribedonto the surface of the columnar support part 45. A glass substrate 46of a package member is placed upon the columnar support part 45, and thecolumnar support part 45 and the glass substrate 46 are joined andsealed by means of, for example, the anode bonding method.

[0108] With the packaging of the embodiment, since there is no steppeddifference on the surface of the columnar support part 45 and nounevenness generated thereupon, and then the overall surface of thecolumnar support part 45 is flattened, the glass substrate 46 can beplaced in close contact with the columnar support part 45, therebyenabling the both to be joined and sealed by means of the anode bonding.That is, since the degree of the overall flatness of a chip having theMEMS device is improved, the degree of freedom with respect to designingthe packaging unique to the MEMS device increases, and the improvementsin the manufacturing process of the MEMS device and the reduction ofcosts can be implemented.

[0109]FIGS. 11A and 11B show an embodiment of a GLV device according tothe present invention.

[0110] As explained in the above-mentioned FIG. 3, a GLV device 61according to the embodiments of the present invention is composed insuch a manner that a plurality of, in this embodiment, six beams 66 [66₁, 66 ₂, 66 ₃, 66 ₄, 66 ₅, 66 ₆] composed of an laminated film of abridge member 64 and driving side electrode 65 are disposed in parallelso as to oppose the common substrate side electrode 63 composed of theconductive semiconductor region (impurities diffused region) that isformed by doping the impurities onto one surface of a semiconductorsubstrate, for example, the silicon mono-crystalline substrate 62.

[0111] As mentioned above, the GLV device 61 alternately varies theheight of the driving side electrodes 65 serving as a light reflectivefilm by the movements of every other beams 66, such as moving closer toor moving away from the substrate side electrode 63, and modulates thestrength of light reflected on the driving side electrode 65 accordingto light diffraction.

[0112] Since the GLV device 61 according to the embodiment is composedof the conductive semiconductor region (impurities diffused region) byforming the substrate side electrode 63 onto one surface of thesemiconductor substrate 62, it is possible to resultantly improve thelight reflectance of the mirror surface of the driving side electrodes65 serving as a reflective film of the beams 66, and to provide the GLVdevice with high light-use efficiency and high performance.

[0113]FIG. 12 shows one embodiment of an optical appliance using the GLVdevice as a light modulation device, to which the above-mentioned MEMSdevice is applied. This embodiment is the case in which the GLV deviceis applied to a laser display.

[0114] A laser display 71 according to the embodiment is used as, forexample, a projector for large-scaled screen, particularly, a projectorof digital images, or an appliance for projecting computer images.

[0115] The laser display 71 is equipped with, as shown in FIG. 12, thelaser beam sources of 72R, 72G, 72B of respective colors of red (R),green (G), blue (B); mirrors 74R, 74G, 74B sequentially providedrespectively on the optical axis of each laser beam source; respectiveillumination optical systems (a group of lenses) 76R, 76G, 76B; and GLVdevices 78R, 78G, 78B functioning as a light modulation device.

[0116] The laser beam sources of 72R, 72G, 72B respectively emit laserbeams of, for example, R (wavelength 642 nm, light output about 3W), G(wavelength 532 nm, light output about 2W), B (wavelength 457 nm, lightoutput about 1.5W).

[0117] Further, the laser display 71 includes a color synthesizingfilter 80 for synthesizing a red color (R) laser beam, green color (G)laser beam, and blue color (B) laser beam, the light strengths of whichare respectively modulated by GLV devices 78R, 78G, 78B; a space filter82; a diffuser 84; a mirror 86; a Galvano scanner 88; a projectingoptical system (a group of lenses) 90; and a screen 92. The colorsynthesizing filter 80 is composed of, for example, a dichroic mirror.

[0118] With the laser display 71 according to the embodiment, respectiveRGB laser beams of light emitted from the laser beam sources of 72R,72G, 72G are incident upon the respective GLV devices 78R, 78G, 78B viaeach of the respective mirrors 74R, 74G, 74B and through respectiveillumination optical systems 76R, 76G, 76B. The respective laser beamsof light are color-classified image signals, which are to besynchronously input in the GLV devices 78R, 78G, and 78B.

[0119] Further, the respective laser beams of light are modulated withrespect to space by being diffracted by the GLV devices 78R, 78G, 78B,and these three color diffracted beams of light are synthesized by thecolor synthesizing filter 80, and only signal components aresuccessively derived by the space filter 82.

[0120] Next, the RGB image signals have laser speckles reduced by thediffuser 84, and via the mirror 86 the signals are spread into space byGalvano scanner 88 synchronous to the signals so as to be projected ontothe screen 92 as full color images by the projecting optical system 90.

[0121] Since the laser display 71 of this embodiment is equipped withthe GLV devices 78R, 78G, 78B that have, as shown in FIG. 11, such acomposition as a light modulation device, the light flux of imagesignals to be emitted improves in comparison with the laser displayusing a conventional light modulation device. As the light flux ofsignals improves, light-use efficiency of laser beams from the laserbeam sources of 72R, 72G, 72G improves.

[0122] The laser display 71 of this embodiment is equipped with the GLVdevices 78R, 78G, 78B corresponding to the respective color laser beamsources 72, and therefore the GLV device according to the presentinvention is capable of being applied to various types of displayshaving other compositions than the above.

[0123] For example, while the light source is made to be a white color,the light modulation devices 78R, 78G, 78B, each of which has adifferent beam width, may compose one pixel to display respective colorsby reflecting only light having each of the wavelengths of Red, Green,and Blue (other light is diffracted).

[0124] Further, it is possible to make a white color light from a singlelight source enter the GLV device 78 through a color wheel thatsynchronizes with image information composed of RGB pixel data.

[0125] Furthermore, when, for example, the single GLV device 78 is usedto be composed such that the device 78 reproduces color information onevery pixel by diffracting light from LED (light-emitting diode) of RGB,it becomes a simplified handy-type color display.

[0126] In addition, the GLV device according to the present inventioncan be used not only in the kinds of projectors such as the laserdisplay of this embodiment but also as an optical switch in variouskinds of optical devices, for example, various transmitting devices forWDM (Wavelength Division Multiplexing) in the optical communications,MUX (Multiplexer: parallel serial transducer/distribution apparatus) orOADM (Optical Add/Drop Multiplexer), OXC (Optical Cross Connect) and thelike.

[0127] Moreover, the GLV device according to the present invention canbe applied to other optical appliances such as a microscopic drawingapparatus that can directly draw, for example, digital images and thelike, a semiconductor exposure apparatus, a printer engine, and thelike.

[0128] Additionally, with the laser display 71 of the presentembodiment, explanations have been made of the laser display thatmodulates with respect to space by means of the GLV devices 78R, 78G,and 78B. However, the GLV device of the present invention can performswitching of information that can be modulated by interfering anddiffracting a phase, the strength of light and the like, and can beapplied to optical appliances using thereof.

1. An electrostatic drive type MEMS device, characterized by comprisinga substrate side electrode and a beam that is disposed to oppose saidsubstrate side electrode and that has a driving side electrode driven byelectrostatic attraction force or electrostatic repulsion force thatacts between the substrate side electrode and said driving sideelectrode, said substrate side electrode being formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate.
 2. An electrostatic drive type MEMS device according to claim1, wherein said conductive semiconductor region is electricallyinsulated from the peripheral region of said semiconductor substratethrough being isolated by insulation by means of selective oxidation, ortrench isolation.
 3. A manufacturing method of an electrostatic drivetype MEMS device, characterized by comprising the processes of: forminga substrate side electrode that is insulated to be isolated from otherparts by doping impurities onto the surface of a semiconductorsubstrate, selectively forming a sacrificial layer including the upperpart of said substrate side electrode, forming a beam having a drivingside electrode on said sacrificial layer, and removing said sacrificiallayer.
 4. A manufacturing method of an electrostatic drive type MEMSdevice according to claim 3, wherein said doping of impurities iscarried out by means of an ion infusion method, a thermal diffusionmethod or a solid phase diffusion method.
 5. An optical MEMS device,characterized by comprising a substrate side electrode and a beam thatis disposed to oppose said substrate side electrode and that has a lightreflective film cum driving side electrode driven by electrostaticattraction force or electrostatic repulsion force that acts between thesubstrate side electrode and said driving side electrode, said substrateside electrode being formed of an impurities-doped conductivesemiconductor region in a semiconductor substrate.
 6. A light modulationdevice, characterized by comprising a substrate side electrode and abeam that is disposed to oppose said substrate side electrode and thathas a light reflective film cum driving side electrode driven byelectrostatic attraction force or electrostatic repulsion force thatacts between the substrate side electrode and said driving sideelectrode, said substrate side electrode being formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate.
 7. A GLV device, characterized by comprising a commonsubstrate side electrode and a plurality of beams that are independentlydisposed in parallel to each other to oppose said common substrate sideelectrode and that each have a light reflective film cum driving sideelectrode driven by electrostatic attraction force or electrostaticrepulsion force that acts between the substrate side electrode and saiddriving side electrode, said substrate side electrode being formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate.
 8. A laser display comprising a laser beam source and a GLVdevice that is disposed on an optical axis of the laser beam emittedfrom said laser beam source to modulate the strength of the laser beam,characterized in that said GLV device includes a common substrate sideelectrode and a plurality of beams that are independently disposed inparallel to each other to oppose said common substrate side electrodeand that each have a light reflective film cum driving side electrodedriven by electrostatic attraction force or electrostatic repulsionforce that acts between the substrate side electrode and said drivingside electrode, said substrate side electrode being formed of animpurities-doped conductive semiconductor region in a semiconductorsubstrate.